The invention relates to an exhaust-gas turbocharger for an internal combustion engine with a cooled compressor wheel.
An exhaust-gas turbocharger which includes an arrangement for cooling the compressor wheel of the exhaust-gas turbocharger is already known (DE 198 45 375 A1). The rear wall of the compressor wheel is cooled by introducing a coolant at a radial distance from an outer edge or outer circumference of the compressor wheel. In order to flow along the rear wall of the compressor wheel therefore, the coolant has to overcome the centrifugal forces generated by rotation of the compressor wheel. Since the compressor wheel, reaches high rotational speeds, these centrifugal forces will only permit inadequate cooling of the back of the compressor wheel. Introducing the coolant at a radial distance from the outer edge or outer circumference of the compressor wheel furthermore means that compressed air can get into the coolant through a radial gap left between the outer wall of the compressor wheel and an inner wall of the housing, so that bubbles are formed on the rear wall. Such bubble formation, however, leads to an unfavorable heat transmission at the back of the compressor wheel, which has an adverse effect on cooling performance.